Aprilaire 720 Series - Principle of Operation; Operating Instructions - Model 720 A; Automatic Digital Humidifier Control Indicator Lights; Blower Activation

90-1235
FIGURE 1: MODEL 60 ADHC (AUTOMATIC MODE)
PRINCIPLE OF OPERATION
The AprilAire 720 Fan-Powered Evaporative Humidier delivers
maximum moisture output with superior water efciency for
ducted HVAC systems.
1. When humidity is low, the humidier control makes a call for
humidity and the solenoid valve opens.
2. Water ows through the orice to the HydroCore.
3. The humidier fan pulls air from the HVAC system through
the HydroCore and evaporation occurs.
4. The HVAC system fan disperses humidied air throughout
the home.
5. Increased output and water conservation are realized with
water recirculation technology. Water may or may not be
noticed in the drain line due to improved efciency.
6. Once humidity levels are reached, the humidier control
deactivates the valve causing the ow of water into the
unit to stop. As recirculated water is no longer needed, a
surge of water may be noticed going down the drain. This is
essential to purge solids left behind during evaporation and
to prevent standing water during long periods of inactivity.
OPERATING INSTRUCTIONS - MODEL 720A
The Model 60 Automatic Digital Humidier Control (ADHC) offers
two modes of operation, Automatic or Manual (see FIGURE 1 for
Automatic mode. See FIGURE 2 on page 4 for Manual mode).
Benets of Automatic mode:
• Control automatically adjusts RH setting based on outdoor
temperature
• Helps prevent excess condensation
• Simple operation with few manual adjustments
AUTOMATIC DIGITAL HUMIDIFIER CONTROL INDICATOR LIGHTS
Service Required: The red light indicates that the humidier is
not operating normally and that service is required.
Change Water Panel: The yellow light indicates that it is time to
change the HydroCore in the humidier (see pages 6 and 7).
Humidier On: The green light indicates that the humidier is
actively adding healthy humidity to your home.
BLOWER ACTIVATION
Setting the BLOWER ACTIVATION switch to ON (see FIGURE 1)
allows the humidier control to activate the HVAC system fan
for maximum humidication. For this setting the humidier is
recommended to be connected to hot water.
This function will operate in two ways:
1. If the HVAC system has been idle for one hour, the humidier
control will activate the HVAC system fan to sample the
air for 3 minutes. If the RH is lower than the set point, the
humidier control will activate the humidier and keep the
fan running.
2. If the RH set point has not been reached by the end of a call
for heat, the control will continue to operate the humidier
and the HVAC system fan.
Once blower activation mode is initiated, the humidier and
HVAC system fan will continue to operate for 2 hours or until the
humidication set point is reached.
When the BLOWER ACTIVATION switch is in the OFF position, the
humidier control will only operate the humidier if the HVAC
system fan or heat is on AND if the RH is lower than the set
point.
NOTE: Humidier output is lower without heat so it is normal for
it to run longer to satisfy humidity requirements.
AUTOMATIC MODE
Your AprilAire Digital Humidier Control is installed in the cold air
return duct. Use the dial to adjust the RH setting and the digital
display to read the current RH.
1. When rst installed, turn the dial to 5, which is within the
normal range.
2. During the next 24-48 hours it may be necessary to adjust
the dial for more or less humidity, depending on your
personal comfort and home’s requirements. Refer to TABLE 3.
3. During the coldest portion of the rst heating season, minor
adjustments may be necessary. This is dependent upon your
home’s construction. Refer to TABLE 3.
English 3